Black aqueous ink composition, ink jet recording process using the same, and recorded matter

ABSTRACT

To provide a black aqueous ink composition for excellent light and gas fastness, an ink set including the ink composition, and an ink jet recording process using the same, the black aqueous ink composition contains at least a trisazo dye represented by Chemical Formula 31.

DETAILED DESCRIPTION OF THE INVENTION

[0001] 1. Technical Field to Which the Invention Belongs

[0002] The present invention relates to a black aqueous ink compositionsuitable for use in ink jet recording, an ink jet recording processusing the same, and recorded matter obtained through recording by therecording process.

[0003] 2. Background Art

[0004] Ink jet recording is a process in which an ink is ejected assmall droplets from a minute nozzle to record characters or images on asurface of a recording medium. Techniques of ink jet recording whichhave been put to practical use include: a method comprising convertingelectrical signals. to mechanical signals with an electrostrictiveelement and intermittently ejecting an ink stored in a nozzle head torecord characters or images on a surface of a recording medium; and amethod comprising bubbling an ink stored in a nozzle head by rapidlyheating that part of the ink which is located very close to the orificeand intermittently ejecting the ink based on the volume expansion causedby the bubbling to thereby record characters or images on a surface of arecording medium.

[0005] The inks for ink jet recording are generally ones prepared bydissolving various dyes in water or an organic solvent or in a mixturethereof, from the standpoints of safety and printing properties.However, the ink jet recording inks are required to satisfy severerrequirements concerning various properties than inks for writingutensils such as fountain pens and ball-point pens.

[0006] In particular, ink jet printers have recently come to be employedfor producing printed matters for advertisement. However, since printedmatters produced with aqueous ink compositions such as those shown aboveare put up not only indoors but also outdoors, they are exposed tovarious lights including sunlight and to the air (which may containozone, nitrogen oxides, sulfur oxides, etc.). There is hence aphenomenon in which they deteriorate in image quality. Deterioration inblack parts is especially significant.

[0007] For the purpose of improving gas fastness (especially ozonefastness) of ink compositions containing dyes as colorants, the disazodye having the following structure has, for example, been proposed. See,for example, Patent Document 1 and Chemical Formula 7 identified below.

[0008] The disazo dye having the following structure has also beenproposed. See, for example, Patent Document 2 and Chemical Formula 8identified below. However, those ink compositions each have a drawbackthat the light fastness and gas fastness thereof are insufficient.

[0009] Patent Document 1 herein is Japanese Patent Laid-Open No.229770/1991 and Patent Document 2, is Japanese Patent Laid-Open No.91576/1991.

[0010] Problems that the Invention is to Solve

[0011] The present invention has been achieved in view of thecircumstances described above, and an object thereof is to provide ablack aqueous ink composition capable of giving printed matters whichare excellent in light fastness and gas fastness and retain high imagequality, preferably a black aqueous ink composition capable of givingprinted matters which are excellent in light fastness, gas fastness, andstorage stability and retain high image quality. Another object of theinvention is to provide an ink jet recording process using the inkcomposition. A still other object of the invention is to providerecorded matter obtained through recording by the recording process.

[0012] Means for Solving the Problems

[0013] The present inventors made investigations on various knowntrisazo dyes and novel trisazo dyes with respect to their light fastnessand gas fastness. As a result, they found that black dyes having thestructure shown below have excellent light fastness and gas fastness andthat these black dyes in which the counter ion (M) is an organicammonium further have excellent storage stability. The invention wascompleted based on these findings.

[0014] 1. The black aqueous ink composition has a feature of containingat least a trisazo dye represented by the following formula 1: ChemicalFormula 9 (all Chemical Formulae are herein below) wherein A representsa hydrogen atom or a carboxyl group (—COOM); R¹, R², R³, and R⁴ eachindependently represent a hydrogen atom, an alkyl group having 1 to 5carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxylgroup, a sulfamoyl group, a carbamoyl group, an acetyl group, a carboxylgroup, a sulfo group, or a halogen atom; Nps represents a group selectedfrom Chemical Formula 10 wherein M is selected from a hydrogen atom, analkali metal, ammonium, and an organic ammonium and B represents a groupselected from Chemical Formula 11 wherein M is selected from a hydrogenatom, an alkali metal, ammonium, and an organic ammonium.

[0015] 2. The black aqueous ink composition of the invention has afeature that the trisazo dye is a trisazo dye represented by thefollowing formula 2: Chemical Formula 12 wherein A represents a hydrogenatom or a carboxyl group (—COOM); R¹, R², R³, and R⁴ each independentlyrepresent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, analkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfamoylgroup, a carbamoyl group, an acetyl group, a carboxyl group, a sulfogroup, or a halogen atom; and M is selected from a hydrogen atom, analkali metal, ammonium, and an organic ammonium.

[0016] 3. The black aqueous ink composition of the invention has afeature that the trisazo dye is a trisazo dye represented by thefollowing formula 3: Chemical Formula 13 wherein A represents a hydrogenatom or a carboxyl group (—COOM); R¹, R², R³, and R⁴ each independentlyrepresent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, analkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfamoylgroup, a carbamoyl group, an acetyl group, a carboxyl group, a sulfogroup, or a halogen atom; and M is selected from a hydrogen atom, analkali metal, ammonium, and an organic ammonium.

[0017] 4. The black aqueous ink composition of the invention has afeature that the trisazo dye is a trisazo dye represented by thefollowing formula 4: Chemical Formula 14 wherein A represents a hydrogenatom or a carboxyl group (—COOM); R¹, R², R³, and R⁴ each independentlyrepresent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, analkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfamoylgroup, a carbamoyl group, an acetyl group, a carboxyl group, a sulfogroup, or a halogen atom; and M is selected from a hydrogen atom, analkali metal, ammonium, and an organic ammonium.

[0018] 5. The black aqueous ink composition of the invention has afeature that the counter ion (M) in the trisazo dye represented by anyof formulae 1 to 4 is an organic ammonium.

[0019] 6. The black aqueous ink composition of the invention has afeature that the counter ion (M) in the trisazo dye represented by anyof formulae 1 to 4 is an organic ammonium derived from a tertiary amine.

[0020] 7. The black aqueous ink composition of the invention has afeature that the tertiary amine is N,N-dimethylethanolamine,triethanolamine, or triisopropanolamine.

[0021] 8. The black aqueous ink composition of the invention has afeature that the trisazo dye is contained in an amount of from 0.1 to12% by weight based on the whole amount of the ink composition.

[0022] 9. The black aqueous ink composition of the invention has afeature of further containing a nitrogen-containing organic solvent.

[0023] 10. The black aqueous ink composition of the invention has afeature that the nitrogen-containing organic solvent is 2-pyrrolidone.

[0024] 11. The black aqueous ink composition of the invention has afeature of further containing a nonionic surfactant.

[0025] 12. The black aqueous ink composition of the invention has afeature that the nonionic surfactant is an acetylene glycol typesurfactant.

[0026] 13. The black aqueous ink composition of the invention has afeature that the nonionic surfactant is contained in an amount of from0.1 to 5% by weight based on the whole amount of the ink composition.

[0027] 14. The black aqueous ink composition of the invention has afeature of further containing a penetrating agent.

[0028] 15. The black aqueous ink composition of the invention has afeature that the penetrating agent is a glycol ether.

[0029] 16. The black aqueous ink composition of the invention has afeature of having a pH as measured at 20° C. of from 7.5 to 10.5.

[0030] 17. The black aqueous ink composition of the invention has afeature of further containing a yellow dye as a complementary color.

[0031] 18. The black aqueous ink composition of the invention has afeature that the yellow dye is C.I. Direct Yellow 86, 132, or 173.

[0032] 19. The black aqueous ink composition of the invention has afeature that it is for use in an ink jet recording process.

[0033] 20. The black aqueous ink composition of the invention has afeature that the ink jet recording process is a recording process usingan ink jet head which forms ink droplets by means of mechanicaldeformations of an electrostrictive element.

[0034] 21. The ink jet recording process of the invention has a featureof comprising ejecting droplets of an ink composition and adhering thedroplets to a recording medium to conduct recording, wherein any of theblack aqueous ink compositions described above is used as the inkcomposition.

[0035] 22. The recorded matter of the invention has a feature of beingobtained through recording with any of the black aqueous inkcompositions described above.

[0036] Mode for Carrying out the Invention

[0037] The ink composition of the invention comprises an aqueous mediumcomprising water or a combination of water and a water-soluble organicsolvent and, contained in the aqueous medium, at least a dye representedby formula 1 given above. The composition may optionally contain ahumectant, viscosity modifier, pH regulator, and other additives.

[0038] Preferred of the dyes represented by formula 1 which can becontained in the ink composition of the invention are dyes representedby formula 2 (Chemical Formula 4), formula 3 (Chemical Formula 5), orformula 4 (Chemical Formula 6). Preferred of the dyes represented byformula 2 are dyes represented by the following formula 5 (ChemicalFormula 15). Preferred of the dyes represented by formula 1 (ChemicalFormula 1), formula 2 (Chemical Formula 4), formula 3 (Chemical Formula5), or formula 4 (Chemical Formula 6) are those in which M in theformula is an organic ammonium from the standpoint of the storagestability of the ink. See, Chemical Formula 15.

[0039] (For formula 5, M is selected from a hydrogen atom, an alkalimetal, ammonium, and an organic ammonium.

[0040] The organic ammonium is represented by (NR⁵R⁶R⁷R⁸)⁺, wherein R⁵,R⁶, R⁷, and R⁸ may be the same and each represent hydrogen (the organicammonium in which all of R⁵ to R⁸ are hydrogen is excluded because it isammonium), an optionally substituted alkyl group having 1 to 5 carbonatoms, an optionally substituted phenyl group, or an optionallysubstituted aralkyl group. Examples of these groups include3-aminopropyl, 2-hydroxyethyl, n-butyl, tert-butyl, 2-cyanoethyl,benzyl,. isopropyl, carboxymethyl, phenyl, m-tolyl, p-tolyl, and1-hydroxyisopropyl. The organic ammonium preferably is an organicammonium obtainable from a tertiary amine. Examples of the tertiaryamine include N-(3-aminopropyl)diethanolamine, N-n-butyldiethanolamine,N-tert-butyldiethanolamine, N-(2-cyanoethyl)diethanolamine,N,N-dibenzyl-2-aminoethanol, 2-di-n-butylaminoethanol,N,N-diethylethanolamine, N,N-dimethylethanolamine,N,N-diisopropylethanolamine, N-ethyldiethanolamine,N,N-bis(carboxymethyl)ethanolamine, N-methyldiethanolamine,N-phenyldiethanolamine, triethanolamine, m-tolyldiethanolamine,p-tolyldiethanolamine, N,N-bis(2-hydroxyethyl)isopropanolamine,N,N-dimethylisopropanolamine, 3-dimethylamino-1-propanol,triisopropanolamine, and N-phenyldiisopropanolamine. More preferred ofthose are the organic ammoniums obtained from N,N-dimethylethanolamine,triethanolamine, and triisopropanolamine. This is because these organicammoniums not only impart ink storage stability but also enable the inkcomposition to be easily regulated in viscosity and not to deterioratethe inertness to the materials constituting various members with whichthe ink composition may come into contact.

[0041] Specific examples of the dye represented by formula 1 includethose whose free acid forms are shown in the following Table 1-1 toTable 1-5 (provided that the dyes shown in Tables 1-1 to 1-3 and 1-5 arein the form of free acid, while in each of the dyes shown in Table 1-4,the M's are a mixture of a sodium ion and an organic ammonium). However,the dye represented by formula 1 should not, of course, be construed asbeing limited to these examples. Those dyes represented by formula I maybe used alone or in combination of two or more thereof.

[0042] A dye represented by formula 5 given above can be obtained, forexample, by conducting coupling reactions (→) in the order of (1), (2),and (3) as shown below. See, Chemical Formula 16.

[0043] Namely, the target dye is obtained through: (1) a step in whichdiazotized anthranilic acid is caused to couple with g-acid; (2) a stepin which the resultant monoazo compound is diazotized and thisdiazotization product is caused to couple with K-acid; and (3) a step inwhich diazotized anthranilic acid is caused to couple with the resultantdisazo compound.

[0044] The trisazo dye represented by formula 1 given above has one ortwo structures each comprising two benzene nuclei separated by an azobond. In this structure, one of the benzene nuclei has a carboxyl groupin an ortho position (relative to the azo bond) and the other benzenenucleus has a hydroxyl or amino group in an ortho position and furtherhas a sulfo group in the other ortho position. It is thought that due tothis structure, the dye retains fastness to light and gases. A moreilluminating explanation is given below on dyes shown below in ChemicalFormula 17, which are represented by formula 5, as an example. Dyeshaving in their molecular structure two structures each surrounded bythe dotted line (e.g., the dyes represented by Chemical Formula 21 toChemical Formula 24, which will be given later) are superior to dyeshaving one structure surrounded by the dotted line (e.g., the dyesrepresented by Chemical Formula 25 and Chemical Formula 26, which willbe given later). As can be presumed from this fact, dyes having two suchstructures (e.g., the dyes represented by Chemical Formula 21 toChemical Formula 24, which will be given later) are preferred of thedyes represented by formula 1.

[0045] See, Chemical Formula 17.

[0046] Namely, when dyes of the kind described above are used in an inkfor ink jet recording, this ink shows a high color density in printedimages and high fastness (fastness regarding light resistance, gasresistance, water resistance, and stability). Although the reasons forthis effect have not been fully elucidated, the following is thought.These dyes have an azo-bond-containing structure comprising acombination of two aromatic rings in which one aromatic ring(anthranilic acid) has a carboxyl group in an ortho position to the azobond group and the other aromatic ring is one which is part of theK-acid or g-acid. This configuration of functional groups is less apt toresult in the formation of impurities in the synthesis by successivecoupling reactions. Because of this, the dye has an exceedingly highpurity and the synthesis does not yield oxides or the like which may becausative of a decrease in fastness.

[0047] The dye represented by formula 1 has satisfactory waterresistance because it has a carboxyl group in the dye structure.Moreover, since the dye further has water-soluble acid groups such assulfo groups, it dissolves in aqueous media in the form of an alkalimetal salt or ammonium salt. In case where an acidic aqueous medium isused, the dye shows reduced solubility. It is therefore preferred toregulate the pH of the ink composition (20° C.) to 7.5 or higher forstably dissolving the dye in a given amount. When inertness to thematerials constituting various members with which the ink compositionmay come into contact is taken into account, it is preferred to regulatethe pH of the ink composition to 10.5 or lower. For more satisfactorilyreconciling these requirements, it is more preferred to regulate the pHof the ink composition to 8.0 to 10.0.

[0048] The amount of the dye represented by formula 1 contained in theink composition of the invention is from 0.1 to 12% by weight, morepreferably from 0.5 to 10% by weight, most preferably from 1 to 8% byweight. In case where the content of the dye represented by formula 1 islower than 0.1% by weight, there is a problem that coloring propertiesor a color density on a recording medium cannot be secured. In casewhere the content thereof exceeds 12% by weight, there is a problem thatit is difficult to regulate the viscosity of the ink composition andproperties such as ejection reliability and nonclogging propertiescannot be secured.

[0049] The ink composition of the invention can contain a yellow dye asa complementary-color dye for the purpose of color regulation. Theyellow dye may be any dye which is yellow. Examples thereof include C.I.Acid Yellow 1, 3, 11, 17, 19, 23, 25, 29, 36, 38, 40, 42, 44, 49, 59,61, 70, 72, 75, 76, 78, 79, 98, 99, 110, 111, 127, 131, 135, 142, 162,164, and 165; C.I. Direct Yellow 1, 8, 11, 12, 24, 26, 27, 33, 39, 44,50, 55, 85, 86, 87, 88, 89, 110, 132, 142, 144, and 173; C.I. ReactiveYellow 1, 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 16, 17, 18, 22, 23, 24, 25,26, 27, 37, and 42; C.I. Food Yellow 3 and 4; and C.I. Solvent Yellow15, 19, 21, 30, and 109. Preferred of these are C.I. Acid Yellow 23 andC.I. Direct Yellow 50, 55, 86, 132, and 173 because use of these yellowdyes facilitates the attainment of ink reliability such as coloringproperties and nonclogging properties. Especially preferred are C.I.Direct Yellow 86, 132, and 173 from the standpoint of impartingsatisfactory light resistance besides producing those effects.

[0050] The ink composition of the invention can further contain ahumectant selected from water-soluble organic solvents having a lowervapor pressure than pure water and/or saccharides. When the ink containsa humectant, water evaporation can be inhibited to keep the ink moist inink jet recording processes. When the humectant is a water-solubleorganic solvent, it can improve ejection stability and facilitateviscosity regulation without changing ink properties. The water-solubleorganic solvent means a medium having the ability to dissolve solutestherein, and is selected from water-soluble solvents which are organicand have a lower vapor pressure than water. Desirable examples of theorganic solvents include polyhydric alcohols such as ethylene glycol,propylene glycol, butanediol, pentanediol, 2butene-1,4-diol,2-methyl-2,4-pentanediol, glycerol, 1,2,6-hexanetriol, diethyleneglycol, triethylene glycol, and dipropylene glycol; ketones such asacetonylacetone; esters such as g-butyrolactone and triethyl phosphate;and furfuryl alcohol, tetrahydrofurfuryl alcohol, and thiodiglycol.Preferred examples of the saccharides include maltitol, sorbitol,gluconic lactone, and maltose. A humectant may be added in an amount ofgenerally from 5 to 50% by weight, preferably from 5 to 30% by weight,more preferably from 5 to 20% by weight, based on the whole amount ofthe ink composition. When the humectant amount is 5% by weight orlarger, the ink can be kept moist. When the humectant amount is 50% byweight or smaller, the ink can be easily regulated so as to have aviscosity suitable for ink jet recording.

[0051] The ink composition of the invention preferably contains as asolvent a nitrogen-containing organic solvent. Examples of thenitrogen-containing organic solvent include1,3-dimethyl-2-imidazolidinone, 2-pyrrolidone, N-methyl-2-pyrrolidone,e-caprolactam, and urea. Such nitrogen-containing solvents may be usedalone or in combination of two or more thereof. The content of thesolvent is preferably from 0.5 to 10% by weight, more preferably from 1to 5% by weight. Contents thereof lower than 0.5% by weight pose aproblem that the dissolution of the colorant according to the inventionis improved little by the solvent addition. Contents thereof higher than10% by weight pose a problem that the solvent impairs the inertness ofthe ink composition to the materials constituting various members withwhich the ink composition may come into contact.

[0052] The ink composition of the invention preferably contains anonionic surfactant as an additive effective for obtaining rapid inkfixing (penetration) and simultaneously maintaining the roundness ofeach dot.

[0053] Examples of the nonionic surfactant for use in the inventioninclude acetylene glycol type surfactants. Specific examples of theacetylene glycol type surfactants include Surfynol 465, Surfynol 104,and Olfin STG (trade names; all manufactured by Nisshin ChemicalIndustry Co., Ltd.). The amount of the nonionic surfactant to be addedis generally from 0.05 to 3% by weight, preferably from 0.5 to 2% byweight. Amounts thereof smaller than 0.05% by weight are undesirable inthat sufficient penetrating properties cannot be obtained. Amountsthereof exceeding 3% by weight are undesirable in that image fogging mayoccur, leading to a decrease in image quality.

[0054] Addition of a glycol ether as a penetrating agent in combinationwith the nonionic surfactant is effective in enhancing penetratingproperties and reducing the bleeding which may occur at the interfacebetween adjacent color inks in color printing. Thus, an exceedinglyclear image can be obtained.

[0055] Examples of the glycol ether for use in the invention includeethylene glycol monobutyl ether, diethylene glycol monobutyl ether,triethylene glycol monoethyl ether, propylene glycol monomethyl ether,dipropylene glycol monoethyl ether, propylene glycol monobutyl ether,dipropylene glycol monobutyl ether, and triethylene glycol monobutylether. The amount of the glycol ether to be added is generally from 3 to30% by weight, preferably from 5 to 15% by weight. In case where theamount thereof is smaller than 3% by weight, the effect of preventingbleeding cannot be obtained. In case where the amount thereof exceeds30% by weight, not only image fogging occurs but also oil separationoccurs, making it necessary to use a dissolution aid for the glycolether. The addition of a dissolution aid results in an increase in inkviscosity to raise ejection difficulties in ink jet heads.

[0056] Other additives may be added to the ink composition of theinvention according to need. Examples thereof include pH regulators suchas triethanolamine and alkali metal hydroxides, water-soluble polymerssuch as sodium alginate, water-soluble resins, fluorochemicalsurfactants, mildew-proofing agents, and rust preventives.

[0057] Examples of methods for preparing the ink composition of theinvention include a method in which the ingredients are sufficientlymixed and dissolved and the resultant solution is filtered underpressure through a membrane filter having an opening diameter of 0.8 mmand then degassed with a vacuum pump to prepare the ink composition.

[0058] The recording process of the invention, which uses the inkcomposition described above, will be explained next. The ink compositionof the invention can be advantageously used especially in the recordingprocess of the invention, which comprises ejecting droplets of the inkcomposition through a minute opening and adhering the droplets to arecording medium to conduct recording. However, it is a matter of coursethat the ink composition of the invention is usable also in applicationssuch as general writing utensils, recording instruments, and penplotters.

[0059] Any of known techniques of ink jet recording can be used. Inparticular, excellent images can be recorded in a method in whichoscillations of a piezoelectric element are used to eject droplets(recording method using an ink jet head which forms ink droplets bymeans of mechanical deformations of an electrostrictive element) and amethod in which thermal energy is utilized.

EXAMPLES

[0060] The invention will be explained below in more detail by referenceto Examples and Comparative Examples. Prior to these, examples of thepreparation of trisazo dyes to be used in the Examples of the inventionare shown.

[0061] The invention should not be construed as being limited by thefollowing Examples.

[0062] Preparation of Trisazo Dye A

[0063] 1) Synthesis of Monoazo Intermediate

[0064] Anthranilic acid (0.2 mol) was diazotized in an ordinary mannerand caused to couple with g-acid (2-amino-8-naphthol-6-sulfonic acid;0.2 mol). This reaction was conducted while regulating the pH of thereaction mixture to 10 to 11.5 by adding an aqueous sodium hydroxidesolution. The resultant precipitate was taken out by filtration toobtain the following monoazo intermediate. See, Chemical Formula 18.

[0065] 2) Synthesis of Disazo Intermediate

[0066] The monoazo intermediate (about 0.2 mol) obtained in 1) above wasdiazotized and caused to couple with K-acid(8-amino-1-naphthol-3,5-disulfonic acid; 0.19 mol). This reaction wasconducted while regulating the pH of the reaction mixture to 3.5 orlower by adding an aqueous sodium carbonate solution. The resultantprecipitate was taken out by filtration to obtain the following disazointermediate. See, Chemical Formula 19.

[0067] 3) Synthesis of Trisazo Compound

[0068] Subsequently, methyl anthranilate (0.18 mol) was diazotized in anordinary manner and caused to couple with the disazo intermediate (about0.19 mol) obtained in 2) above. This reaction was conducted whileregulating the pH of the reaction mixture to 8 to 11 by adding anaqueous sodium hydroxide solution. Salting-out was conducted, and theresultant precipitate was taken out by filtration to obtain thefollowing trisazo compound. See, Chemical Formula 20.

[0069] 4) Synthesis of Trisazo Dye A (M₁ Salt of Compound Example 1)

[0070] The trisazo compound obtained in 3) above was dissolved in water.Sodium hydroxide was added thereto to hydrolyze the trisazo compound at55 to 65° C. and thereby convert the methoxycarbonyl group (—COOCH₃)into a carboxyl group. The resultant reaction mixture was subjected todesalting purification, and ammonia water was then added thereto toadjust the pH of the mixture to 9 to 9.5. Thus, a trisazo dye Arepresented by the following formula (M₁ salt of compound example 1) wasobtained. See, Chemical Formula 21. (In the formula, M₁'s eachindependently are Na or NH₄, the proportion of Na to NH₄ being about3:2.)

[0071] Preparation of Trisazo Dyes B, C, and D

[0072] After the methoxycarbonyl group (—COOCH₃) was converted to acarboxyl group in step 4) in the preparation of trisazo dye A describedabove, concentrated hydrochloric acid was added to the reaction mixtureto adjust the pH thereof to 1 to 2. The dye thus obtained was isolatedby filtration. The resultant press cake of the dye was dissolved inwater with the aid of each of N,N-dimethylethanolamine, triethanolamine,and triisopropanolamine and subjected to desalting purification with areverse osmosis membrane. Thus, trisazo dyes B, C, and D(organic-ammonium salts) represented by the following formulae wereobtained.

[0073] Trisazo Dye B (Compound Example 11), see Chemical Formula 22.

[0074] Trisazo Dye C (Compound Example 12), see Chemical Formula 23.

[0075] Trisazo Dye D (Compound Example 13), see Chemical Formula 24.

[0076] Preparation of Trisazo Dye E

[0077] The same procedure as in the preparation of trisazo dye A wasconducted, except that p-phenedine was used in place of the anthranilicacid used in preparing the trisazo dye A. Thus, a trisazo dye E (M₁ saltof compound example 5) was obtained. See, Chemical Formula 25. (In theformula, M₁'s each independently are Na or NH₄, the proportion of Na toNH₄ being about 3:1.)

[0078] Preparation of Trisazo Dye F

[0079] The same procedure as in the preparation of trisazo dye A wasconducted, except that p-n-butylaniline was used in place of theanthranilic acid used in preparing the trisazo dye A. Thus, a trisazodye F (M₁ salt of compound example 9) was obtained. See, ChemicalFormula 26. (In the formula, M₁'s each independently are Na or NH₄, theproportion of Na to NH₄ being about 3:1.)

[0080] Preparation of Trisazo Dye G

[0081] 1) Monoazo Intermediate Synthesis (1). Methyl anthranilate (0.3mol) was diazotized in an ordinary manner and caused to couple withK-acid (8-amino-1-naphthol-3,5-disulfonic acid). This reaction wasconducted while regulating the pH of the reaction mixture to 1.5 orlower by adding an aqueous sodium carbonate solution. The reactionmixture was stirred overnight and then filtered to take out theprecipitate. The press cake obtained was dissolved in water. Sodiumhydroxide was added thereto to hydrolyze the reaction product at 55 to60° C. and thereby convert the methoxycarbonyl group (—COOCH₃) into acarboxyl group. This reaction mixture was subjected to salting-out, andthe resultant precipitate was taken out by filtration to obtain thefollowing monoazo intermediate. See, Chemical Formula 27.

[0082] 2) Monoazo Intermediate Synthesis (2). Anthranilic acid (0.3 mol)was diazotized in an ordinary manner and caused to couple with g-acid(2-amino-8-naphthol-6-sulfonic acid; 0.3 mol). This reaction wasconducted while regulating the pH of the reaction mixture to 10 to 11.5by adding an aqueous sodium hydroxide solution. The resultantprecipitate was taken out by filtration to obtain the following monoazointermediate. See, Chemical Formula 28.

[0083] 3) Synthesis of Trisazo Compound. The monoazo intermediate (0.1mol) obtained in 2) above was diazotized and caused to couple with themonoazo intermediate (0.1 mol) obtained in 1) above. This reaction wasconducted while regulating the pH of the reaction mixture to 8 to 11 byadding an aqueous sodium hydroxide solution. Salting-out was conducted,and the resultant precipitate was taken out by filtration to obtain thefollowing trisazo dye. See, Chemical Formula 29.

[0084] 4) Preparation of Trisazo Dye G (M, Salt of Compound Example 14).The trisazo dye obtained in 3) above was dissolved in water.Concentrated hydrochloric acid was added thereto to adjust the pHthereof to 1 to 2 and this dye was isolated by filtration. The resultantpress cake of the dye was dissolved in water with the aid of ammoniawater and subjected to desalting purification. Thus, a trisazo dye G (M₁salt of compound example 14) represented by the following formula wasobtained. See, Chemical Formula 30. (In the formula, M₁'s eachindependently are Na or NH₄, the proportion of Na to NH₄ being about 3:1.)

EXAMPLES 1 TO 7 AND COMPARATIVE EXAMPLES 1 AND 2

[0085] Ink compositions of Examples 1 to 7 and Comparative Examples 1and 2 were prepared according to the formulations shown in Table 3 bythe preparation method described above. In the table, the amounts of thecomponents of each ink composition are given in terms of % by weightbased on the whole amount of the ink composition, and the remainder iswater. The dyes used in the Comparative Examples are shown in Table 2.

[0086] The ink compositions described in Examples 1 to 7 and ComparativeExamples 1 and 2 given above were subjected to the following evaluationtests. The results obtained are shown in Table 4. In the evaluationtests, ink jet printer PM-800C (manufactured by Seiko Epson Corp.) wasused to conduct printing of alphabetic characters and graphic printingon PM Photographic Paper (trade name; manufactured by Seiko Epson Corp;Type No. KA420PSK) and PM Matte Paper (trade name; manufactured by SeikoEpson Corp.; Type No. KA450PM).

[0087] Light Fastness Test 1

[0088] Each of the ink compositions described in Examples 1 to 7 andComparative Examples 1 and 2 was charged into an exclusive cartridge forblack for ink jet printer PM800C (manufactured by Seiko Epson Corp.).Using this printer, printing was conducted on PM Photographic Paper andPM Matte Paper while regulating the duty so as to result in an OD(optical density) in the range of from 0.9 to 1.1. The printed mattersthus obtained were allowed to stand for one day in an atmosphere havingordinary temperature and ordinary humidity and insulated from directsunlight, and were then evaluated for light fastness under the followingconditions. First, each printed matter was irradiated with light usingxenon light fastness tester XL-75S (trade name; manufactured by SugaTest Instruments Co., Ltd.) under the conditions of a block panel,temperature of 40° C., relative humidity of 60%, radiation wavelength offrom 300 to 400 nm, and irradiance of 36 W/m² (for 168 hours or 336hours). The printed matter was examined with spectrophotometer GRETAGSPM (manufactured by Gretag Macbeth) before and after the lightirradiation to determine the discoloration (DE) through the irradiation.Conditions for this color measurement were: illuminant D50; noilluminant filter; white standard was absolute white; and viewing angleof 2°. The discoloration was calculated according to the L*a*b* colorsystem as provided for in JIS Z 8729.

ΔE={(L*−L ₀*)²+(a*−a ₀*)2+(b*−b ₀*)²}^(0.5)

[0089] (L*, a*, b*: hue after irradiation

[0090] L₀*, a₀*, b₀*: hue before irradiation).

[0091] From the value of ΔE obtained, the light fastness was evaluatedbased on the following criteria.

[0092] A: ΔE is less than 10.

[0093] B: ΔE is from 10 to less than 20.

[0094] C: ΔE is from 20 to less than 30.

[0095] D: ΔE is 30 or more.

[0096] Gas Fastness Test

[0097] Each of the ink compositions described in Examples 1 to 7 andComparative Examples 1 and 2 was charged into an exclusive cartridge forblack for ink jet printer PM-800C (manufactured by Seiko Epson Corp.).Using this printer, printing was conducted on PM Photographic Paperwhile regulating the duty so as to result in an OD (optical density) inthe range of from 0.9 to 1.1. The recorded matters thus obtained wereallowed to stand for one day in an atmosphere having ordinarytemperature and ordinary humidity and insulated from direct sunlight,and were then evaluated for gas fastness under the following conditions.First, each recorded matter was exposed to ozone with ozoneweatherometer OMS Type H (trade name; manufactured by Suga TestInstruments Co., Ltd.) under the conditions of 24° C., relative humidityof 60%, and ozone concentration of 10 ppm for given periods (4 hours or12 hours). The recorded matter was examined with spectrophotometerGRETAG SPM (manufactured by Gretag Macbeth) before and after the lightirradiation to determine the discoloration (DE) through the irradiation.Conditions for this color measurement were: illuminant D50; noilluminant filter; white standard was absolute white; and viewing angleof 2°. The discoloration was calculated according to the L*a*b* colorsystem as provided for in JIS Z 8729.

ΔE={(L*−L ₀*)²+(a*−a ₀*)2+(b*−b ₀*)²}^(0.5)

[0098] (L*, a*, b*: hue after exposure

[0099] L₀*, a₀*, b₀*: hue before exposure).

[0100] From the value of ΔE obtained, the gas fastness was evaluatedbased on the following criteria.

[0101] A: ΔE is less than 10.

[0102] B: ΔE is from 10 to less than 20.

[0103] C: ΔE is from 20 to less than 30.

[0104] D: ΔE is 30 or more.

[0105] Storage Stability Test

[0106] Each of the ink compositions described in Examples 1 to 7 andComparative Examples 1 and 2 was placed in an amount of 100 g in aheat-resistant glass container. These containers were tightly capped,subsequently stored in a 70° C. thermostatic chamber for 6 days, andthen returned to ordinary temperature. These inks were filtered underreduced pressure through a membrane filter having an opening diameter of0.8 mm and evaluated based on the following criteria.

[0107] A: no abnormality.

[0108] B: precipitate generated.

[0109] [Table 8](Table 4)

[0110] Advantage of the Invention

[0111] As described above in detail, since the black aqueous inkcomposition of the invention contains the trisazo dye represented byformula 1 as a colorant, the invention produces an excellent effect thatthe recorded matter obtained through printing with the ink compositionhas excellent light fastness and gas fastness and retains high imagequality. TABLE 1 Table 1-1 HPLC λmax Name Structure purity (abs.) Com-pound example 1

96.3% 603.2 nm (0.708) 512.4 nm (0.384) Com- pound example 2

97.6% 608.0 nm (0.558) Com- pound example 3

95.2% 601.0 nm (0.558) Com- pound example 4

65.2% 605.2 nm (0.532)

[0112] TABLE 2 Table 1-2 HPLC λmax Name Structure purity (abs.) Com-pound example 5

96.4% 608.0 nm (0.596) Com- pound example 6

83.5% 604.6 nm (0.464) Com- pound example 7

86.1% 597.6 nm (0.529)

[0113] TABLE 3 Table 1-3 HPLC λmax Name Structure purity (abs.) Com-pound example 8

84.5% 608.4 nm (0.394) Com- pound example 9

92.9% 604.2 nm (0.529) Com- pound example 10

84.4% 597.6 nm (0.530)

[0114] TABLE 4 Table 1-4 HPLC λmax Name Structure purity (abs.) Compoundexample 11

Compound example 12

601.6 nm (0.577) 513.2 nm (0.320 Compound example 13

[0115] TABLE 5 Table 1-5 HPLC λmax Name Structure purity (abs.) Com-pound example 14

94.4% 624.4 nm (0.623) Com- pound example 15

95.3% 626.0 nm (0.615) Com- pound example 16

92.7% 621.2 nm (0.618)

[0116] TABLE 6 Table 2 Name Structure C.I. Direct Black 154 (C.I.D.B154)

C.I. Direct Black 168 (C.I.D.B 168)

[0117] TABLE 3 Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex.1 Ex. 2 Colorant Dye of 6 — — — — — — — — Chemical Formula-21 Dye of — —— 6 — — — — — Chemical Formula-22 Dye of — — — — 6 — — — — ChemicalFormula-23 Dye of — — — — — 6 — — — Chemical Formula-24 Dye of ChemicalFormula-25 — 6 — — — — — — — Dye of — — 6 — — — — — — ChemicalFormula-26 Dye of — — — — — — 6 — — Chemical Formula-30 C.I. Direct — —— — — — — 6 — Black 154 C.I. Direct — — — — — — — — 6 Black 168 Otherink Glycerol 10 10 10 10 10 10 10 10 10 components Diethylene 10 — 10 1010 10 — — 10 glycol monobutyl ether Triethylene — 10 — — — — 10 10 —glycol monobutyl ether Triethylene — 3 2 3 3 3 — 6 3 glycol Urea 2 1 — 11 1 4 — — 2-Pyrrolidone 6 3 4 — — — 2 — — Triethanol- 0.6 0.6 0.6 — 0.6— 0.6 0.6 0.6 amine Olfin STG 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4(manufactured by Nisshin Chemical) Proxcel XL-2 0.3 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 (manufactured by AVECIA) Water for Ultrapure water remainderremainder remainder remainder remainder remainder remainder remainderremainder preparation

[0118] TABLE 4 Light resistance test Gas resistance test PM PhotographicPaper PM Matte Paper PM Photographic Paper PM Matte Paper 168 h 336 h168 h 336 h 4 h 12 h 4 h 12 h Example 1 A A A B A B A B Example 2 A A AB B C B B Examle 3 A B B C A B A B Example 4 A A A B A B A B Example 5 AA A B A B A B Example 6 A A A B A B A B Example 7 A A A B A A A AComparative D D D D C D B C Example 1 Comparative B D B C D D B CExample 2 Ink storage stability 70° C., 6 days Example 4 A Example 5 AComparative A Example 1 Comparative A Example 2

[0119] [Chemical Formula-1]

[0120] [Chemical Formula-9]

[0121] [Chemical Formula-31]

[0122] [Chemical Formula-2]

[0123] [Chemical Formula-10]

[0124] [Chemical Formula-32]

[0125] [Chemical Formula-3]

[0126] [Chemical Formula-11]

[0127] [Chemical Formula-33]

[0128] [Chemical Formula-4]

[0129] [Chemical Formula-12]

[0130] [Chemical Formula-5]

[0131] [Chemical Formula-13]

[0132] [Chemical Formula-7]

[0133] [Chemical Formula-8]

[0134] [Chemical Formula-6]

[0135] [Chemical Formula-14]

[0136] [Chemical Formula-15]

[0137] [Chemical Formula-16]

[0138] [Chemical Formula-17]

[0139] [Chemical Formula-18]

[0140] [Chemical Formula-19]

[0141] [Chemical Formula-20]

[0142] [Chemical Formula-21]

[0143] [Chemical Formula-22]

[0144] [Chemical Formula-23]

[0145] [Chemical Formula-24]

In the claims
 1. (currently amended) A black aqueous ink compositioncontaining at least a trisazo dye represented by the following formula1: [Chemical Formula-1] [wherein A represents a hydrogen atom or acarboxyl group (—COOM); R¹, R², R³, and R⁴ each independently representa hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxygroup having 1 to 5 carbon atoms, a hydroxyl group, a sulfamoyl group, acarbamoyl group, an acetyl group, a carboxyl group, a sulfo group, or ahalogen atom; Nps represents a group selected from [Chemical Formula-2](wherein M is selected from a hydrogen atom, an alkali metal, ammonium,and an organic ammonium); B represents a group selected from [ChemicalFormula-3] (wherein M is selected from a hydrogen atom, an alkali metal,ammonium, and an organic ammonium)].
 2. (currently amended) The blackaqueous ink composition of claim 1, wherein the trisazo dye is a trisazodye represented by the following formula 2: [Chemical Formula-4][wherein A represents a hydrogen atom or a carboxyl group (—COOM); R¹,R², R³, and R⁴ each independently represent a hydrogen atom, an alkylgroup having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbonatoms, a hydroxyl group, a sulfamoyl group, a carbamoyl group, an acetylgroup, a carboxyl group, a sulfo group, or a halogen atom; and M isselected from a hydrogen atom, an alkali metal, ammonium, and an organicammonium].
 3. (currently amended) The black aqueous ink composition ofclaim 1, wherein the trisazo dye is a trisazo dye represented by thefollowing formula 3: [Chemical Formula-5] [wherein A represents ahydrogen atom or a carboxyl group (—COOM); R¹, R², R³, and R⁴ eachindependently represent a hydrogen atom, an alkyl group having 1 to 5carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxylgroup, a sulfamoyl group, a carbamoyl group, an acetyl group, a carboxylgroup, a sulfo group, or a halogen atom; and M is selected from ahydrogen atom, an alkali metal, ammonium, and an organic ammonium]. 4.(currently amended) The black aqueous ink composition of claim 1,wherein the trisazo dye is a trisazo dye represented by the followingformula 4: [Chemical Formula-6] [wherein A represents a hydrogen atom ora carboxyl group (—COOM); R¹, R², R³, and R⁴ each independentlyrepresent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, analkoxy group having 1 to 5 carbon atoms, a hydroxyl group, a sulfamoylgroup, a carbamoyl group, an acetyl group, a carboxyl group, a sulfogroup, or a halogen atom; and M is selected from a hydrogen atom, analkali metal, ammonium, and an organic ammonium].
 5. (currently amended)The black aqueous ink composition of claim 1, wherein M in the trisazodye represented by any of formulae 1 to 4 is an organic ammonium. 6.(currently amended) The black aqueous ink composition of claim 1,wherein the organic ammonium is an organic ammonium derived from atertiary amine.
 7. (currently amended) The black aqueous ink compositionof claim 6, wherein the tertiary amine is N,N-dimethylethanolamine,triethanolamine, or triisopropanolamine.
 8. (currently amended) Theblack aqueous ink composition of claim 1, which contains the trisazo dyein an amount of from 0.1 to 12% by weight based on the whole amount ofthe ink composition.
 9. (currently amended) The black aqueous inkcomposition of claim 1, which further contains a nitrogen-containingorganic solvent.
 10. (currently amended) The black aqueous inkcomposition of claim 9, wherein the nitrogen-containing organic solventis 2-pyrrolidone.
 11. (currently amended) The black aqueous inkcomposition of claim 1, which further contains a nonionic surfactant.12. (currently amended) The black aqueous ink composition of claim 11,wherein the nonionic surfactant is an acetylene glycol type surfactant.13. (currently amended) The black aqueous ink composition of claim 11,which contains the nonionic surfactant in an amount of from 0.1 to 5% byweight based on the whole amount of the ink composition.
 14. (currentlyamended) The black aqueous ink composition of claim 1, which furthercontains a penetrating agent.
 15. (currently amended) The black aqueousink composition of claim 14, wherein the penetrating agent is a glycolether.
 16. (currently amended) The black aqueous ink composition ofclaim 1, which has a pH as measured at 20° C. of from 7.5 to 10.5. 17.(currently amended) The black aqueous ink composition of claim 1, whichfurther contains a yellow dye as a complementary color.
 18. (currentlyamended) The black aqueous ink composition of claim 17, wherein theyellow dye is C.I. Direct Yellow 86, 132, or
 173. 19. (currentlyamended) The black aqueous ink composition of claim 1, which is for usein an ink jet recording process.
 20. (currently amended) The blackaqueous ink composition of claim 19, wherein the ink jet recordingprocess is a recording process using an ink jet head which forms inkdroplets by means of mechanical deformations of an electrostrictiveelement.
 21. (currently amended) An ink jet recording process whichcomprises ejecting droplets of an ink composition and adhering thedroplets to a recording medium to conduct recording, wherein a blackaqueous ink composition of any one of claim 1 is used as the inkcomposition.
 22. (currently amended) Recorded matter obtained throughrecording with a black aqueous ink composition of any one of claim 1.